CoAuthors

Michel Tchilibou (LEGOS, France); Rosemary Morrow (LEGOS, France); Guillaume Serazin (LEGOS, France); Bughsin Djath (Helmholtz-Zentrum Geesthacht, Germany)

The tropics are distinguishable from mid latitudes by their small Coriolis parameter vanishing at the equator, large Rossby radius, and strong anisotropic circulation. These peculiarities are at the origin of dynamics that strongly respond to the wind forcing through zonally propagating tropical waves, and of a large range of wavenumbers covering meso and submesoscale interactions. The main tropical meso and submesoscales features are associated with Tropical Instability Waves, but coherent vorticity structures span the tropical band. This study aims to infer the dynamics of the tropical Pacific through spectral EKE and SSH analyses. We point out the sensitivity of the spectra in the equatorial belt to the choice of spectral window and the data length. From the 1/12° resolution DRAKKAR global, model frequency-wavenumber EKE spectra, and their corresponding 1D wavenumber are analyzed to illustrate the latitudinal dependence and the degree of anisotropy of the tropical dynamics with a focus on intraseasonal motions and the large meso submesoscale wavenumber range. SSH spectra are analyzed to raise the observability of such dynamics by altimetry. Estimation of altimetric mesoscale slope is revisited to take account of the variable mesoscale range in the tropics but internal waves flatten the altimetric spectra. A regional 1/36° resolution model with and without explicit tides is used to illustrate the shape of the altimetric spectra